{"id":"GHSA-5q95-hrpc-m3w3","summary":"JLine: ReDoS via `HISTORY_IGNORE` Configuration Variable","details":"### Summary\n\nThe JLine3 `HISTORY_IGNORE` variable is converted into a Java regular expression with\nonly partial escaping. As a result, regex metacharacters other than `*` and `:` are\npassed through to the regex engine. A crafted value such as `(a+)+b` can cause\ncatastrophic backtracking each time a command line is added to history, hanging the\nreader thread at high CPU.\n\n### Details\n\nIn `reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java`,\n`matchPatterns()` converts `HISTORY_IGNORE` into a regex:\n\n```java\nfor (int i = 0; i \u003c patterns.length(); i++) {\n    char ch = patterns.charAt(i);\n    if (ch == '\\\\') {\n        ch = patterns.charAt(++i);\n        sb.append(ch);\n    } else if (ch == ':') {\n        sb.append('|');\n    } else if (ch == '*') {\n        sb.append('.').append('*');\n    } else {\n        sb.append(ch);\n    }\n}\nreturn line.matches(sb.toString());\n```\n\nThis logic translates wildcard syntax but does not escape regex metacharacters such as\n`(`, `)`, `+`, `?`, `{`, `}`, `[`, and `]`. Those characters therefore reach the Java\nregex engine unchanged.\n\nAffected source location:\n- `reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java`\n- `matchPatterns(String patterns, String line)`\n\n### PoC\n\n1. Configure `HISTORY_IGNORE` to a malicious pattern, for example:\n\n```sh\nset history-ignore \"(a+)+b\"\n```\n\n2. At the JLine prompt, enter a long non-matching line:\n\n```text\naaaaaaaaaaaaaaaaaaaaaaaaaaax\n```\n\n3. Press Enter.\n\nExpected result:\n- The prompt does not return.\n- The reader thread consumes high CPU.\n\nReproduction environment:\n- JLine3 on x86_64 Linux\n- OpenJDK 25.0.2\n\n### Impact\n\nThis is a denial-of-service vulnerability caused by catastrophic regex backtracking.\nApplications embedding `org.jline:jline-reader` are impacted if they allow\n`HISTORY_IGNORE` to be configured through user configuration or application settings.\nThe issue is lower severity than the interactive editor findings because the attacker\nmust control configuration, but it can still reliably hang a reader session.\n\n### Suggested Fix\n\nThe safest fix for the current git head is to stop treating arbitrary `HISTORY_IGNORE`\ncontent as a regex. Instead, escape all characters by default and translate only the\nintended JLine wildcard syntax (`*`) and separator syntax (`:`).\n\nSuggested patch:\n\n```diff\ndiff --git a/reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java b/reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java\n--- a/reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java\n+++ b/reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java\n@@\n         StringBuilder sb = new StringBuilder();\n         for (int i = 0; i \u003c patterns.length(); i++) {\n             char ch = patterns.charAt(i);\n             if (ch == '\\\\') {\n                 ch = patterns.charAt(++i);\n-                sb.append(ch);\n+                sb.append(Pattern.quote(Character.toString(ch)));\n             } else if (ch == ':') {\n                 sb.append('|');\n             } else if (ch == '*') {\n                 sb.append('.').append('*');\n             } else {\n-                sb.append(ch);\n+                sb.append(Pattern.quote(Character.toString(ch)));\n             }\n         }\n         return line.matches(sb.toString());\n```\n\n### Credits\n\nThis issue was identified by Michał Majchrowicz and Marcin Wyczechowski, members of the AFINE Team.","aliases":["CVE-2026-77420"],"modified":"2026-09-23T18:15:03.944840213Z","published":"2026-09-23T18:12:05Z","database_specific":{"cwe_ids":["CWE-1333"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-09-23T18:12:05Z","nvd_published_at":null},"references":[{"type":"WEB","url":"https://github.com/jline/jline3/security/advisories/GHSA-5q95-hrpc-m3w3"},{"type":"WEB","url":"https://github.com/jline/jline3/pull/2012"},{"type":"WEB","url":"https://github.com/jline/jline3/pull/2018"},{"type":"WEB","url":"https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541"},{"type":"WEB","url":"https://github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae"},{"type":"PACKAGE","url":"https://github.com/jline/jline3"},{"type":"WEB","url":"https://github.com/jline/jline3/releases/tag/4.3.1"},{"type":"WEB","url":"https://github.com/jline/jline3/releases/tag/jline-3.30.15"}],"affected":[{"package":{"name":"org.jline:jline-reader","ecosystem":"Maven","purl":"pkg:maven/org.jline/jline-reader"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"fixed":"4.3.1"}]}],"versions":["4.0.0","4.0.10","4.0.11","4.0.12","4.0.13","4.0.14","4.0.15","4.0.16","4.0.2","4.0.3","4.0.4","4.0.5","4.0.6","4.0.7","4.0.8","4.0.9","4.1.0","4.1.1","4.1.2","4.1.3","4.2.0","4.2.1","4.3.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-5q95-hrpc-m3w3/GHSA-5q95-hrpc-m3w3.json"}},{"package":{"name":"org.jline:jline-reader","ecosystem":"Maven","purl":"pkg:maven/org.jline/jline-reader"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"fixed":"3.30.15"}]}],"versions":["3.10.0","3.11.0","3.12.0","3.12.1","3.13.0","3.13.1","3.13.2","3.13.3","3.14.0","3.14.1","3.15.0","3.16.0","3.17.0","3.17.1","3.18.0","3.19.0","3.2.0","3.20.0","3.21.0","3.22.0","3.23.0","3.24.0","3.24.1","3.25.0","3.25.1","3.26.0","3.26.1","3.26.2","3.26.3","3.27.0","3.27.1","3.28.0","3.29.0","3.3.0","3.3.1","3.30.0","3.30.1","3.30.10","3.30.11","3.30.12","3.30.13","3.30.14","3.30.2","3.30.3","3.30.4","3.30.5","3.30.6","3.30.7","3.30.8","3.30.9","3.4.0","3.5.0","3.5.1","3.5.2","3.6.0","3.6.1","3.6.2","3.7.0","3.7.1","3.8.0","3.8.1","3.8.2","3.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-5q95-hrpc-m3w3/GHSA-5q95-hrpc-m3w3.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}